/**
 * 
 */
package meituan;

import java.util.Scanner;

/**
 * @author zhongfang
 *
 */
public class 大富翁游戏 {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		int n=new Scanner(System.in).nextInt();
		int[] dp=new int[n+1];
		for (int i = 1; i <= n; i++) {
			dp[i]=1;
			for (int j = i-1; j>=1; j--) {
				dp[i]+=dp[j];
			}
		}
		System.out.println(dp[n]);
	}
}
